WASHINGTON, Jan 13 (Reuters) - A top U.S. senator on Friday called for wider federal scrutiny into Fiat Chrysler Automobiles NV's marketing of diesel-powered SUVs, as British regulators sought answers from the Italian-American automaker in the aftermath of Volkswagen AG's emissions scandal.

The call came as the company faced possible fines of up to $4.6 billion as a result of another investigation, by the U.S. Environmental Protection Agency.

Volkswagen AG on Wednesday agreed to pay the largest ever U.S. criminal fine levied on an automaker to settle charges that it conspired for nearly 10 years to cheat on diesel emission tests.

On Thursday, the EPA accused Fiat Chrysler of violating the law by using hidden software to allow excess diesel emissions to go undetected in about 104,000 vehicles. The EPA said they were "illegally sold" because the software was not disclosed to regulators.

UK regulators said on Friday they were urgently seeking information from the EPA over its allegation.

Fiat Chrysler has marketed the SUVs as "eco-diesels" which are "clean by nature" and exceed emissions requirements. The 2014-2016 diesel Ram 1500 and Jeep Grand Cherokee pickups under investigation won several green car awards.

The FTC and a Fiat Chrysler spokesman declined to provide immediate comment.

The EPA allegation stemmed from a review of all diesel vehicles after the agency had launched a probe into German carmaker Volkswagen in September 2015. Fiat Chrysler could face fines of up to $4.6 billion, the agency said.

Fiat Chrysler shares closed 22 cents lower at $9.73 on Friday, a day after falling sharply on concerns about the potentially large fines facing the company.

The FTC, which had also scrutinized Volkswagen marketing, helped win buyback offers for about 500,000 VW diesel owners and significant additional compensation of $5,000 to $10,000 each.

Fiat Chrysler said on Thursday the Justice Department was also investigating the emissions issue.

The EPA and California Air Resources Board told Fiat Chrysler they believed its undeclared emissions software allowed vehicles to generate excess pollution in violation of the law.

Fiat Chrysler Chief Executive Sergio Marchionne angrily rejected the allegations on Thursday, saying there was no wrongdoing and the company had never attempted to create software to cheat emissions rules by detecting when the vehicle was in test mode.

(Reporting by David Shepardson; Editing by Dan Grebler and Richard Chang)